Stupid question re Defoulers

[Canadian Crimson]

Getting a set of defoulers to get rid of my CEL. does it really matter which way the bend goes of just whatever is convenient?

Sponsored

 

[Duece McCracken]

Getting a set of defoulers to get rid of my CEL. does it really matter which way the bend goes of just whatever is convenient?

Well, you'll want them angled upwards to prevent moisture from pooling on them and fouling the sensors. Yes it smokes them, I've eaten a bunch on other ecoboost platforms with poor geometry.

 

[Canadian Crimson]

Well, you'll want them angled upwards to prevent moisture from pooling on them and fouling the sensors. Yes it smokes them, I've eaten a bunch on other ecoboost platforms with poor geometry.

Good point never even though about moisture. I was stuck on forward or backward .

 

[Duece McCracken]

Good point never even though about moisture. I was stuck on forward or backward .

Sensor wire length helps dictate, but I've always put the bung opening towards front of the car, and a 15-30 degree angle to keep moisture from entering the sampling holes.

Rocking meowless longtubes for about 20k now, E85 tuned, all emissions active, no CEL or readiness problems. The chef's kiss! Lol

 

[Robottrainer]

Getting a set of defoulers to get rid of my CEL. does it really matter which way the bend goes of just whatever is convenient?

Let me tell you about a tale of woe I just went through with this. Not sure what year yours is. mine is a 2021.

I replaced the oem cats with GESI green cats. it took alot of fabbing and modifying the drivers side manifold. it worked great until I got the efficiency codes after 2 months.

I tried the defoulers. they work BUT...Ford uses what's called Forward-Aft-O2-Sensor-Control. FAOSC. it uses the rear sensor to bias the front sensor as they age as well as monitoring the cats and adjusting the front o2 sensor for emissions.

The defoulers screws this up. in my case, over a few drive cycles, started to bias rich. it hit 10% when I decided this wasn't desirable. some say it doesn't adjust it much. From experience it does.

Tuner software no longer let's you disable the rear sensors, FAOSC, or MIL codes. no tuner will do it either.

My advice? Just get used to the light or reverse what's causing it. with this error, it automatically disables FAOSC.

I put mine back to stock.

 

[Upallnight91]

Let me tell you about a tale of woe I just went through with this. Not sure what year yours is. mine is a 2021.

I replaced the oem cats with GESI green cats. it took alot of fabbing and modifying the drivers side manifold. it worked great until I got the efficiency codes after 2 months.

I tried the defoulers. they work BUT...Ford uses what's called Forward-Aft-O2-Sensor-Control. FAOSC. it uses the rear sensor to bias the front sensor as they age as well as monitoring the cats and adjusting the front o2 sensor for emissions.

The defoulers screws this up. in my case, over a few drive cycles, started to bias rich. it hit 10% when I decided this wasn't desirable. some say it doesn't adjust it much. From experience it does.

Tuner software no longer let's you disable the rear sensors, FAOSC, or MIL codes. no tuner will do it either.

My advice? Just get used to the light or reverse what's causing it. with this error, it automatically disables FAOSC.

I put mine back to stock.

100% correct. I have noticed this as well. The defoulers can cause the long term fuel trims to go out about 10 from where they would normally be due to messing with the FAOSC calculations. What I did to correct this was drilled the small hole in the defouler out larger. Slowly make the holes bigger untill you find the perfect balance that causes the fuel trims to not spike, yet also doesnt kick a CEL for not having cats. The drill bit size that ended up working the best for me was a 3/8". Otherwise just drill yours out slowly untill you find the sweet spot (requires clearing KAM between each driling and test to get back to baseline)
I had to figure this out because I know without the rear o2's you wont have FAOSC, and I also wanted a catless exhaust and no CEL's. AED claims you should never go WOT on a car that has a CEL on due to o2's or cats, as it uses some other strategy in that condition that is not good (can't remember the specifics on that just remember its not good).

On a side note. After running this setup for about a year and a half I started getting a CEL stating the rear o2's where moving too slowly from rich to lean. I chased that down to carbon starting to clog the little hole in the defouler. I slide the original drill bit (that was used to drill the hole out to its current size) down the hole of the defoulers to clean out the carbon and that fixed that CEL. So keep in mind if using defoulers they may need to be cleaned out every 10 to 15K miles.

 

[Logan@Lethal]

Getting a set of defoulers to get rid of my CEL. does it really matter which way the bend goes of just whatever is convenient?

As others have stated, you want to go 90/upward. This helps with e85 (moisture) build up preventing fouling the o2.
https://www.lethalperformance.com/lethal-performance-90-degree-02-spacer.html

 

[Robottrainer]

100% correct. I have noticed this as well. The defoulers can cause the long term fuel trims to go out about 10 from where they would normally be due to messing with the FAOSC calculations. What I did to correct this was drilled the small hole in the defouler out larger. Slowly make the holes bigger untill you find the perfect balance that causes the fuel trims to not spike, yet also doesnt kick a CEL for not having cats. I cant remember the exact size drill bit that I used to get that perfect balance but if anyone needs to know just let me know and I can dig it up. Otherwise just drill yours out slowly untill you find the sweet spot (requires clearing KAM between each driling and test to get back to baseline)
I had to figure this out because I know without the rear o2's you wont have FAOSC, and I also wanted a catless exhaust and no CEL's. AED claims you should never go WOT on a car that has a CEL on due to o2's or cats, as it uses some other strategy in that condition that is not good (can't remember the specifics on that just remember its not good).

On a side note. After running this setup for about a year and a half I started getting a CEL stating the rear o2's where moving too slowly from rich to lean. I chased that down to carbon starting to clog the little hole in the defouler. I slide the original drill bit (that was used to drill the hole out to its current size) down the hole of the defoulers to clean out the carbon and that fixed that CEL. So keep in mind if using defoulers they may need to be cleaned out every 10 to 15K miles.

I tried everything and although it gets rid of the light and you can get ones with different pills to do what you describe, I could not get the 02s or heaters to set.

 

[Upallnight91]

I tried everything and although it gets rid of the light and you can get ones with different pills to do what you describe, I could not get the 02s or heaters to set.

Bummer. I just checked and the size hole I found worked for mine was a 3/8". One thing I did notice is only high quality rear o2's will work right with the drilled out defoulers. I'm currently using NTK. I'm sure the OEM will be good too. But cheaper ones just don't get hot enough to work right

 

[Robottrainer]

Bummer. I just checked and the size hole I found worked for mine was a 3/8". One thing I did notice is only high quality rear o2's will work right with the drilled out defoulers. I'm currently using NTK. I'm sure the OEM will be good too. But cheaper ones just don't get hot enough to work right

Ran brand new Motorcrafts.

 

[Upallnight91]

Ran brand new Motorcrafts.

Bummer it didn't work out for you. I'm currently using just cheap shorter or normal lenght defoulers. No J hook or anything fancy. They need to be as close to the exhaust stream as possible with just a slight restriction (in my case 3/8" hole) to avoid screwing up the fuel trims yet also keep the CEL off (in case someone in the future reads this and attempts this)

 

[Coyotebawl]

Surely with all the guys that have gone catless in boosted applications in fear of blowing one of the cats out have some input on these issues being described in this thread with the FAOSC and what not and a fix to this problem.

 

[Upallnight91]

Surely with all the guys that have gone catless in boosted applications in fear of blowing one of the cats out have some input on these issues being described in this thread with the FAOSC and what not and a fix to this problem.

I would think so but most people seem to believe the rear o2's are there only to monitor the performance of the cats. As that was the case before wide bands where used for the upstream o2's. Probably why many are ok removing the rear o2's and shutting them down in the tune (back when shutting them down was a option).

 

[Robottrainer]

Surely with all the guys that have gone catless in boosted applications in fear of blowing one of the cats out have some input on these issues being described in this thread with the FAOSC and what not and a fix to this problem.

Used to be able to turn that stuff off. Not anymore.

 

[Coyotebawl]

Yeah the good old days , but that is why I am interested to see what catless people are doing to correct the fuel trim issue that Faosc causes since they aren't able to turn off the rear 02's

Sponsored